Silent chain driving transmission



Jam. l i924 J. F. MCCANN SILENT CHAIN DRIVING TRANSMISSION Filed May '7, 1925 MINI .I HV

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narrar arrasa@ tl'HN FRANCES MGCANN, @E SPRINGFIELD, MASSACHUSETTS, ASSEGNB T0 DUCK- WORTH CHAIN' MANUFACTUBNG CMPANY, @F SPRINGFIMJD, MASSACHUSETTS.

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application ala any v, ieee. semi no. cantes.

.To all whom z't may concer/1t:

Beit known that l, JOHN FRANCIS Mo- CANN, a citizen of the United States, and a resident of Springfield, -in the county of Hampden and State of Massachusetts, acting for the Duckworth Chain & Manufacturing Company, also of county o Hampden and State of Massachusetts; have invented certain new and useful llmprovements in Silent Chain 'Driving 'lransinissiony of which the following is a specification.

rl`his invention relates to round hollow split pins, used between chain links that are to be hinged together, and has special refer-f ence to .a pin ofthis construction, which due to a narrow split lengthwise of the pin', gradually closes when"v under tension, thus relieving the inside bearing surface of the inclosing links, of excessive frictional wear. This split construction also allows lubricating oil to seep throughthe narrow split in pin, to outside bearing surface of said in, thus insuring a maximum amount of lu rication where needed.

The hollow construction ol the pin also allows air and lubricating oil to circulate on inside of|said in, drawing rictional heat lfrom the outside earing surface, thus maintaining a cool, heat resisting bearing surface.

One object of the invention is the reduction to a minimum of the friction in a chain joint, and consequently the production of a chain in which the lengthening or stretching, due to wear in the joints, shall be negligible.

The only means by which silent cham driving can be made practicable, lies in the construction of a chain Whose pitch shall not change perceptibly by long use, since 1n? chains where stretch is not eliminated thej pitch between the chain and sprocket wheels soon varies to such a degree as to destroy both the sprocket Wheels and the chain. Stretching is eliminated in the present construction due to the slight closing of the hollow .split pin when under tension, thus relieving the inside bearing surface of the chain links from excessive rictional wear.

Having in view the purpose and end above outlined the invention consists in the con-v struction, arrangement, and combination of parts hereinafter fully `described and set forth in the claim.

ln the accompanyi drawing which forms a part of this specification Flg. l represents a side 'elevation of a silent type drivunit.

ing chain, withhollow split pins therein, forming a joint. Fig. 2 represents in plan, a portionpoif a drive chain wherein each link is, in ellect composed ol several plates placed side by side, the plates of each link alternating `with and overlapping the .ends of those in the adjacent link. 'lhe hollow pins are shown in this view peened over after spacing washers H are placed over ends between the links and ends ol pins. Fig. 3 represents a side elevation of an individual link of this sort separated. Figs. 4 and 5 represent side and end elevation, respectively, the round hollow split pin being shown separated rom the driving links ol the chain.

Referring to Figs. l to 3, A. represents the hollow split pin assembled lwith driving links lB which constitute a silent chain driving Referring to Figs. l and 5, C represents the hollow split pin, l) showing the narrow opening running lengthwise, shoulder to shoulder ol pin. E represents rolled shoulder, which unlike the rest of pin is closed tightly and rolled down to a diameter less than the body diameter of pin between the shoulders.

Referring to Fig. l the exact coaction of the round hollow split pin A and chain links B is as follows, when the tension of the driving load is exerted at F-Fl the round hollow in A due to the` narrow split between shou ders, and the spring temper heat treatment which said pins are subjected to, gradually closes together for an instant relieving the abnormal tension on links l, until the chain has assed to negative side of drive, thereby eliminating the intense rictional wear on the inside of hole in the links at G which would obviously take place if pin A was of absolute solid construction instead of the hollow and split construction heretofore described.

Having described the nature and objects i of the invention, I now desire to secure as Ypatented the following claim: 

